This is a UKMLA-centred history guide about painful swollen leg.
Introduction
You can divide causes of a painful swollen leg can be divided into unilateral vs bilateral and acute vs chronic. It is important to establish this early as it will alter the differentials that you will consider during your history taking. If pain is a prominent feature, then the most likely causes are under unilateral, acute leg swelling.
Presenting Complaint
Site
Unilateral vs Bilateral
Whole leg – Lymphoedema, DVT
Lower leg – Achilles tear, gastrocnemius tear, cellulitis, DVT, compartment syndrome
Ankles – Amlodipine, Charcot joint
Posterior to knee – Baker’s cyst, popliteal aneurysm
Ascending – Heart failure, nephrotic syndrome, venous insufficiency
Quality/Character
Cramping – Intermittent claudication, lymphodedema
Burning – Cellulitis
Pulsating – Bakers cyst, popliteal aneurysm
Pressure – DVT, lymphodema
Non-painful – Heart failure, nephrotic syndrome, amlodipine
Intensity
– Compartment syndrome is characterised by severe pain.
– Cellulitis and DVTs can range from mild pain to severe.
Timing
Has the swelling changed over time?
Does the swelling come and go?
Did the pain and/or swelling come on suddenly or slowly?
Acute with sudden onset
Gastrocnemius tear
Achilles tear
Baker’s cyst rupture
Compartment syndrome
Trauma resulting in fractures, haematomas etc
Acute with progression
DVT
Cellulitis
Amlodipine
Chronic (over weeks to months)
Heart failure
Nephrotic syndrome
Lymphoedema
Associated Symptoms
Erythema – Can be indicative of cellulitis and DVT.
Skin breaks and fevers – Very suggestive of cellulitis.
Frothy urine – Nephrotic syndrome
Exertional dyspnoea and paroxysmal nocturnal dyspnoea – Heart Failure
Aggravating/Alleviating Factors
Classically venous insufficiency improves when the patient raises their legs and worsens throughout the day.
Precipitating Event
– Skin breaks such as insect bites, scratches and cuts can precipitate cellulitis.
– Long haul flights and immobilisation can precipitate DVTs.
– Recent medication changes, such as starting Amlodipine or reducing diuretic meidcation can explain symptoms.
Differentials
It is important to demonstrate to the examiner that you are aware of the common differentials and are asking questions to support or refute your working differentials.
Key features of common differentials are summarised in the tables below.
Acute Unilateral
| Differential | Features |
|---|---|
| Cellulitis | Spreading erythema, warmth in the leg, fever, skin breaks such as an insect bite or open wound and discharging pus |
| Deep Vein Thrombosis (DVT) | Leg significantly more swollen than unaffected leg, erythema, warmth, oedema, and risk factors for VTE such as recent immobility, active cancer, recent surgery, personal history of previous VTE and coagulopathies. |
| Gastrocnemius/Achilles tear | History of running or jumping at time of symptom onset, feeling a popping sensation, sudden onset pain and previous injuries to the muscles or tendons in the area. |
| Trauma | Usually suggested by the mechanism of injury and sudden onset of symptoms. |
Less common causes of an acute, unilateral, painful swollen leg include:
- Compartment syndrome
- Ruptured Baker’s cysts
- Abscess formation
Acute Bilateral
| Differential | Features |
|---|---|
| Medication change | Common examples include starting amlodipine and reducing or stopping a diuretic. |
| Heart Failure | Dyspnoea, paroxysmal nocturnal dyspnoea, and cardiac risk factors. Pain is not a common feature. |
Chronic
The majority of chronic causes of leg swelling are bilateral, but can on occasion present asymmetrically.
| Differential | Features |
|---|---|
| Venous insufficiency | Pain and swelling associating with prolonged standing, varicose veins, hyperpigmentation and relief with elevation of legs. |
| Abdominal or pelvic malignancy | Weight loss, bloating, dyspepsia, nausea and vomiting, change in bowel habit, change in periods and night sweats. Pain in the limbs is a less prominent or absent feature, but DVTs can be caused by these malignancies. |
| Lymphoedema | Pitting oedema of the whole leg, previous radiotherapy, or surgery on limb. Lymphoedema is usually a diagnosis of exclusion. This means that other causes must be ruled out first. |
| Heart Failure | Dyspnoea, paroxysmal nocturnal dyspnoea, and cardiac risk factors. Pain is not a common feature. |
| Cirrhosis | Jaundice, weight loss, pruritis, abdominal distention, pale stools and dark urine. Pain is not a common feature. |
| Nephrotic syndrome | Frothy urine from proteinuria. Pain is not a common feature. |
Red Flags
There are serious causes/emergencies that present with a unilateral painful swollen leg. It is important to demonstrate that you are considering this and asking red flag questions to screen for them.
If there are any symptoms or risk factors suggestive of a DVT, you should enquire about symptoms of pulmonary embolism such as dyspnoea, palpitations, syncope and haemoptysis. This is because a DVT can progress to a PE if the clot breaks free and travels to the pulmonary vessels.
Compartment syndrome is an emergency. It typically presents following trauma to a limb, crush injuries or post immobilisation of a limb e.g. in a plaster cast. The hallmark features of compartment syndrome are the six P’s. These are:
- Pain (out of proportion to the clinical findings, and worse on passive movement)
- Pallor
- Pulselessness
- Perishingly cold
- Paraesthesia (late sign)
- Paralysis (late sign, very bad prognostic factor)
Background
In any history you will ask about past medical history, medications, allergies, social history, and family history. In a history about a painful swollen leg, you can show how much you know about the various causes by explicitly asking about the following things:
Past Medical History
Previous DVT/PE increases the risk of VTE significantly, as does active cancer and certain coagulopathies.
Recent surgery can predispose a person to DVTs, compartment syndrome and post operative infections.
Personal history of varicose veins, pregnancy and obesity can predispose patients to venous insufficiency.
Previous radiotherapy to the affected limb can cause lymphoedema.
Family History
Family history of DVT/PE increases the risk of VTE.
Social History
A history of running might indicate a muscular injury, hiking or walking in long grass might predispose a person to insect bites and scratches that can lead to infection.
Author and Editor – Dr James Mackintosh
Last updated 07/01/24
